Hydrogenation liquefaction of coal employing zinc catalysts



Patented Aug. 5, 1952 HYDROGENATION LIQUEFACTION OF COAL EMPLOYING ZINC CATALYSTS Henry H.

' Pelipetz, Venetia, Pa.,

Storch, Pittsburgh, and Michail G. assignors to the United States of America as represented by the Scoretary of the Interior No Drawing. Application April 13, 1949, Serial No. 87,372

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 2 Claims.

The invention herein described and'claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to the liquefaction of coal and its conversion products to obtain liquid products, by means of hydrogenation in the presence of catalysts.- It is .known that when coal is heated to such high temperatures as 450 C. in the presence of active catalysts under high hydrogen pressures such as 1000 pounds or higher that in the process hydrogen is consumed; and gaseous, liquid, andsolid products result. The liquid product of primary liquefaction is complex in structure, and consists of materials that are liquid at atmospheric conditions and distillable without decomposition within a reasonable range of temperature. The liquid product carries dissolved and suspended semi-solid and solid matter. These amounts vary with the extent of hydrogenolysis.

Untreated coal contains only about percent of benzene-soluble material. The solubility of hydrogenated coal in this solvent increases with the extent of hydrogenation. Therefore, solubility in benzene has been used to determine the extent of coal liquefaction. Because of the ease of measuring the amount of benzeneinsoluble material, the percentage of liquefaction is determined on this basis. The percent liquefaction is based on the organic matter in the benzene-insoluble material; it was obtained by the formula Percent liquefaction= l l Original coal-benzene-insoluble .Originalcoal the amount being expressedon the ash-free, dry basis of the coal. r

The present invention relates more particularly to methods for effecting the liquefaction of coal by high temperature hydrogenation wherein finely divided alloys of zinc or certain mixtures of finely divided zinc with other metals are employed as catalysts. Alloys of zinc, comparing favorably in the high order of liquefaction with tin are: Zinc-tin, zinc-antimony, and zincarsenic. Likewise, powdered mixtures of zinc with tin, zinc with antimony, and zinc with arsenic give high percentages of liquefaction.

The present invention is a continuation-in-part of our U. S. Patent application, Serial No.

' 60,393, filed on 2 November 16, 1948, now abandoned.

It has been previously proposed to destructively hydrogenate coal employing finely divided metals.

, There are several patents thereon. Patent literature shows too the importance of volatile halogens as catalysts in the primary liquefaction of coal.

Evidence obtained from the, experimental'work leading to this invention indicates that destructive hydrogenation of coal involves three reactions: First, the initial cracking of the. complex, high molecular weight compounds of which coal is composed, results in the production of a semi-liquid asphalticmaterial; second, the hydrogenation of asphaltic material with the formation of oils; and third, hydrogenation of. the oily productsto produce light fractions.

All these reactions are catalytic, and use of tin compoundshas been proven to be satisfactory.

However, tin is both expensive and hard to get because of geographical locations in which it exists in a natural state. So the use of other catalysts which would promote liquefaction of coal yet would be more accessible and less ex- ,pensive is desirable. Similarly, the replacement of tin by a catalyst which is less expensive due to the inclusion of less expensive substance with the tin is desirable.

In accordance with the present invention, finely divided zinc alloys or finely divided mixtures of zinc with other metalsare employed as catalysts to effect in a positive mannerthe extent of coal liquefaction. We have found that by the addition of such catalysts to the .chargathe order of percent of coal liquefaction substantially approximates that which is achieved by the employment of finely divided tinalone T In order to furth illustrate theinve'ritiomthe examples below are given, which, however, should not be construed as limiting the invention. Example I has been includedfor comparative purposes, that the order of coal liquefaction, wherein the standard tin catalyst has been used, may function as a basis for com parison. 7

EXAMPLE I [For comparison] A typical Pittsburgh-bed (Bruceton) coal is finely ground and made into a paste with an equal part by weight oftetralin. One percentzof tin is-added to this paste and the-mixture. autoclaved with hydrogen under about 1000 ps i.

That the satisfactory yield in percent of liquefaction of coal and also the effectiveness of our processs catalysts, as compared with tin may T Pement Pemn, stand out distinctly, a table is presented below, Dm-aionorreaction. hours 8%?" p g g ig g 5 wherein the conditions of operation, that is, inie e tial hydrogen pressure, reaction temperature, time of duration, are analogous: Initial hydrogen 400 80.0 67.2 400 gm 44,7 pressure, 1000 p. s. 1. g., reaction temperature, 400 450 0.; duration of reaction, 60 minutes. Runs 415 car 49.3 415 85.9 22.0 m were made both in the absence and in the pres- 415 ence of a hydrocarbon liquid pasting 011 which proves that the latter is not necessary.

Table I Charge in grams Percent Percent Run No. of liqueof asphalt Coal Vehicle Catalyst memo formed .5Sn+.275NH4Cl 86.6 26.0 50 83.1 21.9 50 89.8 27.0 so 00.45 37.0 50 80.2 26.4 50 55.5 20.2

Inruns 1011 and 274 supra which embody the process in the use of zinc'ontimony and zinc-tin alloy, respectively, the analysis of the alloy components was 50 percent Z11, 50 percent ab, and 50 percent Zn, 50 percent S n, respectively.

In this and the two succeeding examples, the reaction pressure becomes about 2000, varying somewhat with the temperature. For that reason, it seems best to specify the initial pressure, which in each example was 1000 p. s. 1. hydrogen pressure.

EXAMPLE II .When a similar mixture of coal and tetralin is hydrogenated under the same conditions but with one percent of a powdered zinc-antimony alloy added as the catalyst to this paste, the extent of coal liquefaction is slightly lower than inthe above example, but yet good at the corresponding higher temperature after 1 to 3 hours duration.

Temp l Percent Percent Duration of reaction, hours a C of coal of asphalt liquefied formed EXAMPLE III When a similar mixture of ground coal and tetral n, containing 0.5 percent tin and 0.5 percent of zinc-antimony alloy as the catalyst, is autoclaved with hydrogen under 1000 p. s. -i. initial hydrogen pressure, the results shown in the From Example III, it will be seen that when 50 percent of the tin had been replaced by an equal quantity of a zine-antimony alloy the percent of coal liquefaction was the equal of that in Example I, but for one run.

While we have thus described the process of our invention in a specific manner and under designated conditions, we wish it to be understood that our invention is not limited to the manner and conditions above described, but is adaptable to a widerange of temperatures, pressures, and times of treatment. Particular conditions will vary usually with the type of coal material being processed and the yield and products distribution desired, as is well known in the art.

Temperatures of from 400 to 600 C. and pressures of 30 to 200 atmospheres are the preferred conditions for carrying out our invention. N evertheless, satisfactory results can be obtained within the temperature range 275 to 700 C. or above, and pressures may range from as low as about 5 atmospheres up to as high as 1000 atmospheres. The time of operation may vary from about onehalf to three hours.

The proportion of catalyst in the charge introduced into the converter should be sufficient to complete the process in a practical time and usually will be within the range of from 0.1 to about 10 parts of catalyst per parts of the coal-oil paste. While the catalyst may be recovered from the reaction products, any excess would not be economical; and we prefer to add the catalyst in amounts of 0.5 to 1 part by weight to each 100 parts by weight of coal-oil paste charged to the converter.

As used in this specification and the appended claims, the term coal is intended to include, and should be understood as including, all types, classes, and ranks of solid bituminous fuels such as anthracite coal, bituminous coal, semi-bitu- 'minous coal, subbituminous coal, brown" coal, lignite, peat, and the like. The term pasting liquid will be understood to include various liquids, more particularly an oil from liquid products from coal hydrogenation, coal carboniza't'ion tars, oils from crude petroleum distillation, or such oxygenated carbon compounds as the phenols, for. example, cresol.

Obviously, many modifications and variations in the invention as heremoeiore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the impending claims:

We claim as our invention:

1. A process for producing liquid products by the hydrogenation of coal, the improvement which comprises reacting coal at temperatures of about 275-700 C. with hydrogen under superatmospheric pressure in the presence of a catalyst comprising a finely divided alloy of zinc with antimony, thereby producing a high order of percentage of coal liquefaction, said catalyst being essentially the sole catalytic material employed in said hydrogenation.

2. A process for producing liquid products by the hydrogenation of coal, the improvement which comprises reacting coal, admixed with an oil which has been derived in part at least from liquid products from a prior coal hydrogenation, at temperatures of about 275-700 C. with hydrogen under superatmospheric pressure in the presence of a catalyst comprising a finely divided alloy of zinc with antimony, thereby producing 6 a high order of percentage of coal liquefaction, said catalyst being essentially the sole catalytic material employed in said hydrogenation.

HENRY H. STORCH. MICHAIL G. PELIPETZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,890,439 Pier Dec. 6, 1932 1,894,770 Jennings Jan. 17, 1933 2,159,281 Marecaux May 23, 1939 2,325,072 Pier et a1 July 27, 1943 2,464,271 Storch et al Mar. 15, 1949 FOREIGN PATENTS Number Country Date 300,703 Great Britain Nov. 12, 1928 22,040/35 Australia Mar. 30, 1935 

1. A PROCESS FOR PRODUCING LIQUID PRODUCTS BY THE HYDROGENATION OF COAL, THE IMPROVEMENT WHICH COMPRISES REACTING COAL AT TEMPERATURES OF ABOUT 275*-700* C. WITH HYDROGEN UNDER SUPERATMOSPHERIC PRESSURE IN THE PRESENCE OF A CATALYST COMPRISING A FINELY DIVIDED ALLOY OF ZINC WITH ANTIMONY, THEREBY PRODUCING A HIGH ORDER OF PERCENTAGE OF COAL LIQUEFRACTION, SAID CATALYST BEING ESSENTIALLY THE SOLE CATALYTIC MATERIAL EMPOLYED IN SAID HYDROGENATION. 